Your story is set in a very different world to any of my stories. I don't think I've ever written someone's title prefixing their name; these are also called honorifics
I do have a similar problem with my police procedural/psychological thrillers, of how to write ranks and different sections of the police force. I usually write them in full when first introducing a character, then revert to the abbreviated form. Thus, it's Detective Chief Inspector, followed thereafter by DCI.
Going back to how one is addressed in polite society, I used to get a kick out of receiving birthday cards, while growing up, with Master
Whybrow on the envelope. I don't know if this was more of an English practice, but it made me feel posher and mightier than normal.
My friend Brian didn't like it so much, but then his surname was Bates....